David Beckham's metatarsal could be forgiven for envying all the attention. Daniel Carter's groin was everywhere in New Zealand this week, following Sunday's announcement that a torn tendon had ruled the All Black fly-half out of the remainder of the Rugby World Cup.

This spotlight-hogging body part had deprived the host team of their most important player – in a sense their two most important players: Dan Carter the playmaker and Dan Carter the goal-kicker. Until Sunday, the talismanic No10's groin had been best known to New Zealanders for its role at the centre of an underpants marketing campaign. Now it was the talk of the country. Schedules were cleared to broadcast special lunchtime news bulletins. Newspaper front pages were torn up. Naturally enough, a Twitter account was immediately launched with the name @DCartersGroin. It second post: "Ouch."

The image of Carter lying anguished on the ground, hands shielding his pelvis, forehead straining to burrow into the soil, was ubiquitous. The injury had been sustained during an innocuous goal-kicking session on the eve of the All Blacks' final pool game against Canada. With Richie McCaw absent, Carter, in his 86th Test and with a record 1,250 points to his name, had been chosen to captain the side for the first time.

"It's devastating for Daniel," said the All Blacks coach, Graham Henry, announcing the news. "This was going to be his pinnacle … this was his scene, this World Cup in New Zealand and it was going to be his big occasion."

The news delivered "the biggest shock of the tournament", says Spiro Zavos, author of How to Watch the Rugby World Cup 2011 and a sports columnist who has covered every World Cup since the first in 1987. "Everything seemed to be going so well. Here is one of the great players in the history of the game, he's playing for the All Blacks; the All Blacks haven't won since 1987; they're playing at home; the tournament has been incredibly successful, in terms of the support of New Zealanders and the visiting supporters. And then, suddenly, the worst possible scenario."

On Monday, Carter limped into a crowded press conference, broadcast live by New Zealand's main television channels. "To be named All Black captain – something very special – and to have that taken away from you through an injury and then later to find out that my dream of being involved in the World Cup is now over … it's pretty gut-wrenching and disappointing," he said. "But I have to get over that and continue to think positively and try and help the guys in whatever way I can."

Carter also had advice for the rest of us: "I encourage everyone to move on."

That exhortation was clearly central to the decision to put Carter in front of the media so swiftly. Earlier in the day, a clinical psychologist wheeled out by Radio New Zealand's Morning Report had warned that the anxiety sparked by Carter's defective groin could "spread like a bushfire across the country". Karen Nimmo told the programme: "If you think about it psychologically, it's a wound that opened in 1991, and we've been putting sticking plaster on it ever since, so when you get a blow like this, it rips the sticking plaster off, and unleashes our fears, and the spiral of negative thinking begins."

There was nothing fanciful about that warning – this is a country, after all, where one in three people cares more about who wins the World Cup than about the result of next month's general election, pollsters say – but, actually, it was not to be. The embers of panic burnt out remarkably quickly, leaving New Zealanders free to return to their favourite off-field pastime of this World Cup: raging at the bloody International Rugby Board.

And yes, there was talk of little else – at least a dozen newspapers devoted editorials to the question of All Black World Cup hopes post-Carter. But the mood for the most part was, almost startlingly, unhistrionic. Of those editorials, the Marlborough Express's was typical. "For those who want to take off a national day of mourning at the news, get a grip," it chided. "It's a setback, for sure, but no disaster."

Grant Fox, the man who wore No10 on his back the first, and only, time New Zealand won the World Cup, in 1987, is pleasantly surprised by the response. "I think there was an initial shock – of all the guys, we didn't want it to happen to Daniel – but I think we've moved on really quickly," he says. "We feel terribly for Daniel, his dream's been shattered. [But] largely, with the odd exception, it's been, 'Well, it's happened, can't change it, we've just got to get on with it.' And I actually think it's been quite a mature reaction, for the most part. It's not all doom and gloom."

The severity of the injury, its lack of ambiguity, is cruel for Carter but good for the team and its supporters. It was immediately clear he would miss the rest of the World Cup, denying any oxygen to the will-he-won't-he-make-it conjecture that bedevilled, say, Beckham's metatarsal dramas.

"It's good that there's no speculation," says Fox. "Not from Daniel's point of view, of course, but for the country's sanity. It's very clear that there's no comeback from this. That resigns you to the fact you have to carry on. You're not in a mode of waiting around, of what-if."

And so Carry On it is – literally, for the likes of The Colin Slade Fan Club, whose newly created Facebook page ("We need to bloody get behind this bloke" – 6,000 followers and counting) sports a poster emblazoned with "Keep Calm and Carry On Colin". An admirable slogan, though it could be argued that if Slade reproduces his wobblier moments from outings against Japan and Tonga, simply Carry On Colin might be more like it.

Fox's advice for the stand-in is simple. "Just be Colin Slade. Do what you do well. You're not Daniel Carter, you don't have to emulate Daniel Carter, you don't have to try and so what he does. Do what Colin Slade does best."

For Zavos, a New Zealander based in Australia, the loss of Carter – "arguably the best No10 New Zealand has ever produced" – reduces the All Blacks from "a Rolls-Royce team to a BMW team". But they remain the likeliest side in the competition. The All Blacks' odds lengthened on the news, but only slightly. They remain favourites by some distance. Keep calm, then, and get on with it.

That sentiment seems widely to be shared among All Black supporters. If nothing else, the broken groin has blown away any risk of hubristic complacency. But, given the string of World Cup disappointments from 1991 on – most recently in 2007, when Carter hobbled off the field midway through the second half in that quarter-final loss to France – it feels a fragile calm. The prospect of a tournament-ending injury to the team's other great talent, the captain, Richie McCaw, and what it might do to All Black followers, is almost unthinkable. Fetch the engines.

McCaw was ruled out of half the Super 15 competition with the Canterbury Crusaders following surgery for a stress fracture in his right foot. He has missed two of the All Blacks' four games in the World Cup so far – most recently owing to a recurrence of pain in the foot. Barring a late withdrawal, he will lead the All Blacks in their quarter-final against Argentina, a game most expect the home side to win comfortably. Captain McCaw will then be rested, repaired, injected, whatever it takes, for what could be the toughest game of the tournament, a semi-final against Australia or South Africa. He and his coach call it "niggly". Probably he'll be fine.

But along the way, it's perhaps just as well that New Zealand continues to describe that niggle as a foot problem. For superstition's sake at least, better not to refer to the more specific location of his injury: a metatarsal.